| 摘要 |
PURPOSE:To expand a jump range only by an actuator and to shorten the average access time of an optical disk device by permitting the position sensor of an optical head to detect the track jump available range of the actuator. CONSTITUTION:A control circuit 5 calculates and transmits the distance that an optical axis moves from its present position to a target track. The value is D/A-converted 6 and transmitted to an adder 7. On the other hand, the actuator 1 transmits the output of the position sensor to the adder 7. In such a case, variation of the output of the position sensor when the actuator shifts the optical axis by one track, and the variation of the output value when the actuator 1 shifts a conversion circuit 6 by one track area the same. At the same time, polarity code inverted according to whether the optical axis shifts to the inner periphery of the optical disk or to its outer periphery are also associated with said variation. Consequently, the addition output shows the distance that the optical axis shifts from the neutral point of the actuator.
|
